WO2013171951A1

WO2013171951A1 - Lasing device

Info

Publication number: WO2013171951A1
Application number: PCT/JP2013/001637
Authority: WO
Inventors: 山本　敦樹; 西村　哲二
Original assignee: パナソニック株式会社
Priority date: 2012-05-18
Filing date: 2013-03-13
Publication date: 2013-11-21
Also published as: CN103988378A; EP2852012B1; US8897331B2; CN103988378B; JP5810270B2; US20140247855A1; EP2852012A1; EP2852012A4; JPWO2013171951A1

Abstract

In this lasing device, when the lasing device is activated from an idle state, a resident gas inside a gas circulation path and an optical resonator is discharged from a gas discharge valve, which has been opened by a gas pressure controller. During a time interval calculated by an open time calculator from the immediately preceding idle time of the lasing device, a laser medium gas present inside the line between a laser medium gas supply and a gas supply valve is discharged, together with the resident gas, through the gas supply valve which has been opened by the gas pressure controller. The number of valves used is decreased thereby, reducing costs, as well as minimizing consumption of the laser medium gas.

Description

Laser oscillator

The present invention relates to a laser oscillation device using a laser medium gas.

Laser oscillators are widely used for cutting various materials and shapes, welding, machining, etc., because the workpiece can be machined in a non-contact manner and with little thermal influence.

In particular, a gas laser oscillation device such as a CO ₂ gas laser using a mixed gas mainly composed of CO ₂ as a laser medium gas is widely used because of its excellent laser beam characteristics and relatively high output. .

Such a gas laser oscillation device has an optical resonator and a gas circulation path connected to the optical resonator. The laser medium gas that has become high temperature due to excitation by discharge in the optical resonator is cooled when it is circulated through the gas circulation path.

In the gas circulation path, a blower for circulating the laser medium gas is interposed.

A gas cylinder in which a mixed gas is pre-filled is generally used as the laser medium gas supply device, and a resin or metal piping structure member is used for piping between the gas cylinder and the gas supply valve of the laser oscillation device. However, there is a small pinhole in this piping structure member. For example, in a CO ₂ gas laser oscillation device, only He in the mixed gas leaks selectively depending on the size of this pinhole. As a result, the mixing ratio of the laser medium gas staying in the piping between the gas cylinder and the gas supply valve of the laser oscillation device may change, and stable laser output may not be obtained.

First, a conventional laser oscillation device will be described. A conventional laser oscillation apparatus is shown in FIG.

FIG. 7 is a piping system diagram of a laser gas supply system that supplies gas to an air supply pipe 910 of a laser gas circulation system of the gas laser oscillation device. Laser gas is supplied from a laser gas cylinder 914 to an air supply pipe 910 through a primary pressure regulator 915, a pipe 916, a filter 917, a pressure regulator 918, a valve 919, a valve 920, a rapid supply flow meter 921, and a constant flow meter 922. Is done. The pressure in the air supply pipe 910 is measured by the pressure sensor 923. Further, the gas in the air supply pipe 910 is discharged by the vacuum pump 924 through the rapid exhaust valve 925 or the constant exhaust valve 926. As shown in FIG. 7, the laser medium gas staying in the pipe 916 in the section from the gas cylinder 914 to the gas supply pipe 910 of the gas laser oscillator is discharged by the discharge valve 927 and the timer 928 when the gas laser oscillator is started. I was doing.

FIG. 8 is an open / close sequence diagram of each valve in the conventional gas laser oscillation apparatus. In the conventional laser oscillation device in FIG. 7, the discharge valve 927 is opened while the internal gas of the laser oscillation device before supplying gas from the gas cylinder 914 is exhausted (while both the

valves

925 and 926 are open). . As a result, the laser medium gas staying in the pipe 916 is discharged to the outside when the laser oscillation device is started to stabilize the laser output (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 04-080979

However, in the laser oscillation device according to the prior art, a dedicated discharge valve 927 is required. Further, the opening time of the discharge valve 927 is set to the maximum time for discharging the volume of the pipe 916 connecting the gas cylinder 914 to the laser oscillation device. For this reason, when the stop time of the laser oscillation device is short, more laser medium gas than necessary is discharged to the outside.

Therefore, the present invention provides a laser oscillation device that reduces the number of valves used, reduces costs, and suppresses consumption of the laser medium gas.

The laser oscillation device of the present invention is a laser oscillation device that continuously or intermittently supplies a laser medium gas from the outside. The laser oscillation device of the present invention includes an optical resonator, a gas circulation path, a laser medium gas supply device, a gas discharge pump, a gas pressure detector, a gas pressure controller, a blower, and a current detector. A stop time counter, a storage device, and an open time calculator. The gas circulation path is connected to the optical resonator. The laser medium gas supply device supplies a laser medium gas to the gas circulation path or the optical resonator via a gas supply valve. The gas discharge pump discharges the laser medium gas from the gas circulation path or the optical resonator via the gas discharge valve. The gas pressure detector detects the gas pressure of the laser medium gas in the gas circuit or the optical resonator. The gas pressure controller controls the gas supply valve and the gas discharge valve based on the gas pressure detected by the gas pressure detector. The blower is provided in the gas circulation path. The current detector detects a blower driving current of the blower. The stop time counter counts the stop time when the laser oscillation device is stopped. The storage device stores correlation information between the stop time and the blower driving current. The open time calculator calculates the open time of the gas supply valve when the laser oscillation device is started based on the information stored in the memory. When the laser oscillation device is started from a stopped state, the staying gas in the gas circulation path and the optical resonator is discharged from a gas discharge valve opened by the gas pressure controller. During the time calculated by the open time calculator from the previous stop time of the laser oscillation device, the laser medium gas in the pipe between the laser medium gas supply and the gas supply valve is opened by the gas pressure controller. The gas is discharged together with the staying gas through the gas supply valve.

As a result, even when the mixing ratio of the laser medium gas staying in the piping between the gas cylinder and the gas supply valve of the laser oscillation device changes while the laser oscillation device is stopped, only the necessary amount of the retained gas is emitted from the laser oscillation device. Can be discharged outside. Thereby, the number of used valves can be reduced, the cost can be reduced, and the consumption of the laser medium gas can be suppressed.

FIG. 1 is a configuration diagram showing a laser oscillation apparatus according to an embodiment of the present invention. FIG. 2A is a graph showing the correlation between the laser medium gas density and the blower drive current according to the embodiment of the present invention. FIG. 2B is a graph showing the correlation between the stop time of the laser oscillation apparatus and the laser medium gas density according to the embodiment of the present invention. FIG. 2C is a graph showing a correlation between the stop time of the laser oscillation apparatus and the blower driving current according to the embodiment of the present invention. FIG. 3 is an open / close sequence diagram of each valve of the laser oscillation apparatus according to the embodiment of the present invention. FIG. 4 is a flowchart showing the operation of the laser oscillator according to the embodiment of the present invention, mainly explaining the initial setting procedure. FIG. 5 is a graph for explaining the principle of calculating the gas supply valve opening time according to the embodiment of the present invention. FIG. 6 is a graph for calculating the optimum gas supply valve opening time according to the embodiment of the present invention. FIG. 7 is a piping system diagram of a laser gas supply system of a conventional gas laser oscillation apparatus. FIG. 8 is an open / close sequence diagram of each valve of the conventional laser oscillation device.

(Embodiment 1)
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, the optical resonator 1 includes a partial reflection mirror 2 and a total reflection mirror 3 installed so as to face the partial reflection mirror 2.

A gas circulation path 6 is connected to the optical resonator 1. The laser medium gas circulates in the laser medium gas path constituted by the optical resonator 1 and the gas circulation path 6 by the blower 4 whose rotation is controlled to a constant rotational speed by the inverter 8.

Also, the drive current of the blower 4 is detected by the current detector 9 installed inside the inverter 8.

The heat exchanger 5 is interposed in the gas circulation path 6, and the laser medium gas circulating in the laser medium gas path is cooled by the heat exchanger 5.

In the optical resonator 1, discharge excitation is performed by a high voltage power source (not shown), and the laser medium gas is compressed and pumped in the blower 4, so that the laser medium gas becomes a high temperature.

Therefore, the laser medium gas circulating in the laser medium gas path is cooled by the heat exchanger 5 part, so that the optical resonator 1 part does not become abnormally heated.

One heat exchanger 5 is located downstream of the optical medium 1 in the flow of the laser medium gas (hereinafter referred to as the downstream side) and upstream of the blower 4 in the flow of the laser medium gas (hereinafter referred to as the following). Located upstream). Furthermore, the other heat exchanger 5 is located downstream of the blower 4. Thereby, the laser medium gas heated to high temperature is immediately cooled.

The laser medium gas is supplied from the gas cylinder 30 through the gas supply valve 10 to the laser medium gas path constituted by the optical resonator 1 and the gas circulation path 6. The gas cylinder 30 is a laser medium gas supplier and is installed outside the laser oscillation device 20. In the present embodiment, the gas supply valve 10 is connected to the optical resonator 1.

The laser medium gas circulating in the laser medium gas path constituted by the optical resonator 1 and the gas circulation path 6 is discharged out of the laser medium gas path through the gas discharge valve 11 by the vacuum pump 12. The gas discharge valve 11 is connected to the gas circulation path 6 on the upstream side of the blower 4. However, the present invention is not limited to this, and it may be connected to other places in the gas circulation path 6.

The gas supply valve 10 and the gas discharge valve 11 are composed of electromagnetic valves, and are controlled to be opened and closed by a gas pressure controller 14 described later.

That is, the gas pressure of the laser medium gas in the optical resonator 1 needs to be constantly controlled to a predetermined operation gas pressure suitable for stably obtaining the intensity of the laser beam 7.

Therefore, in the present embodiment, the gas pressure of the laser medium gas circulating in the laser medium gas path constituted by the optical resonator 1 and the gas circulation path 6 is detected by the gas pressure detector 13. An electric signal proportional to the gas pressure detected by the gas pressure detector 13 is output to the gas pressure controller 14 as a gas pressure signal. In the present embodiment, the gas pressure detector 13 is connected between the gas circulation path 6 and the gas discharge valve 11. However, the present invention is not limited to this, and the gas circulation path 6 and the optical resonator 1 may be connected.

The gas pressure controller 14 performs opening / closing control of the gas supply valve 10 and the gas discharge valve 11 so that the gas pressure of the laser medium gas in the optical resonator 1 becomes a predetermined operation gas pressure.

Next, the correlation between the stop time of the laser oscillation device and the blower drive current will be described with reference to FIGS. 2A to 2C.

The work amount of the blower 4 increases in proportion to the density of the laser medium gas. As the work amount of the blower 4 increases, the drive current from the inverter 8 increases. This blower drive current is detected by a current detector 9 built in the inverter 8.

Therefore, as shown in the graph of FIG. 2A, the blower drive current Ix increases in proportion to the density ρx of the laser medium gas. When this blower drive current Ix is expressed by a mathematical formula, the formula (1) is obtained, and the slope α is represented by the formula (2).

Ix = α · ρx (1)
Inclination α = (Ia−Ib) / (ρa−ρb) (2)
If there is a small pinhole or the like in the pipe from the gas cylinder 30 which is a laser medium gas supply device to the gas supply valve 10, for example, in a CO ₂ gas laser oscillation device, depending on the size of the pinhole, the He in the mixed gas Only selectively leaks. As a result, the mixing ratio of the laser medium gas staying in the pipe between the gas cylinder 30 and the gas supply valve 10 of the laser oscillation device changes.

When the laser oscillation device is stopped, the mixing ratio of the remaining laser medium gas continues to change. In this case, as shown in the graph of FIG. 2B, the density ρx of the staying laser medium gas increases with the lapse of the stop time of the laser oscillation device.

When the relationship of the variables shown in the above two graphs is integrated and replaced with the relationship of the drive current Ix ′ of the blower 4 with respect to the stop time of the laser oscillation device, the graph of FIG. As shown in the graph of FIG. 2C, the drive current Ix ′ of the blower 4 also increases in proportion to the stop time of the laser oscillation device. In terms of mathematical formulas, they are represented by formulas (3) and (4).

Ix ′ = β · Tx ′ + Id (3)
Inclination β = (Ic−Id) / Tc (4)
Next, the operation when the gas supply valve 10 and the gas discharge valve 11 are operated according to the valve opening / closing sequence shown in FIG. 3 will be described.

The gas pressure when the laser oscillator is started is A. First, the vacuum pump 12 is turned on by the activation of the laser oscillation device. Subsequently, the gas discharge valve 11 and the gas supply valve 10 are opened. As a result, the laser medium gas is discharged from the gas circulation path 6 and the optical resonator 1 by the vacuum pump 12 via the gas discharge valve 11. At the same time, the laser medium gas staying in the pipe between the gas cylinder 30 and the gas supply valve 10 of the laser oscillation device is combined with a new laser medium gas from the gas cylinder 30 via the gas supply valve 10. To the gas circulation path 6 and the optical resonator 1.

Therefore, the laser medium gas staying in the pipe is eventually discharged to the outside by the vacuum pump 12 as soon as it is supplied to the laser oscillation device 20.

The gas supply valve 10 does not need to be synchronized with the opening timing of the gas discharge valve 11 if the opening timing is constant until the gas pressure reaches B.

After that, when the gas supply valve 10 is closed, the gas pressure is reduced to B. When the gas pressure becomes B, the gas discharge valve 11 is closed, the gas supply valve 10 is opened, the laser medium gas is supplied to the gas circulation path 6 and the optical resonator 1, the inverter 8 is turned on, and the blower 4 rotates. start.

When the gas pressure becomes C, the gas discharge valve 11 is opened and the gas supply valve 10 is closed. When the gas pressure becomes D, the gas supply valve 10 is opened, and when the gas pressure becomes C again, the gas supply valve 10 is closed. Thereafter, the gas supply valve 10 and the gas discharge valve are controlled by the gas pressure controller 14 so that the gas pressure is between C and D according to the detection value of the gas pressure detector 13 until the laser oscillation device is stopped. 11 is controlled to open and close.

The blower 4 reaches an arbitrary rotational speed before and after the timing when the gas pressure becomes C, and thereafter is controlled at a constant speed.

Next, the calculation of the opening time of the gas supply valve 10 when the laser oscillator is started will be described with reference to FIGS. FIG. 4 is a flow chart showing the operation of the laser oscillator of the present embodiment, mainly explaining the initial setting procedure. 5 and 6 are graphs showing the basis of calculation in the initial setting.

After the laser oscillation device 20 is installed in the use environment and the piping from the gas cylinder 30 to the laser oscillation device 20 is laid, initial setting for calculating the open time of the gas supply valve 10 is performed.

In step S01 of FIG. 3, it is determined whether initial setting is necessary.

When the initial setting is selected, step S02 is executed. In step S02, the laser medium gas staying in the pipe from the gas cylinder 30 to the laser oscillator 20 and in the gas circulation path 6 and the optical resonator 1 is sufficiently exhausted. After replacing the laser medium gas, the gas mixture ratio is set to a normal state, and the blower drive current is detected by the current detector 9 and stored as Id in a storage device mounted on the open time calculator 15. This drive current Id is the same as that shown in the graph of FIG. 2C.

In step S03, the laser oscillation device is stopped and left for a predetermined time Tc. This stop time Tc is counted by the stop time counter 16 and stored in a storage device mounted on the open time calculator 15. Tc is the same as that described in the graph of FIG. 2C. In addition, the predetermined time Tc should just be more than the time which can detect the drive current difference of the below-mentioned fan, and should just be determined arbitrarily.

In step S04, the laser oscillation device is started after a predetermined time Tc is stopped, and the drive current when the blower 4 is controlled at a constant speed is detected by the current detector 9, and this is mounted on the open time calculator 15 as Ic. Store in memory. This drive current Ic is the same as that shown in the graph of FIG. 2C. However, in step S03, while the laser oscillator is activated and the gas pressure is reduced from A to B, the gas supply valve 10 is not opened but kept closed.

In step S05, the slope β representing the correlation between the laser oscillation device stop time and the blower drive current is calculated by the open time calculator 15 according to the equation (4) and stored in the storage device mounted on the open time calculator 15.

In step S06, the laser oscillation device is stopped and left for an arbitrarily defined time Te. The stop time Te is counted by the stop time counter 16 and stored in a storage device mounted on the open time calculator 15.

In step S07, the laser oscillation device is started after the time Te is stopped, and the laser oscillation device is operated in the sequence shown in FIG. The opening time tf of the gas supply valve at this time is arbitrarily determined and stored in a storage device mounted on the opening time calculator 15.

The drive current when the blower 4 is controlled at a constant speed is detected by the current detector 9 and stored as If in the storage device mounted on the open time calculator 15.

FIG. 5 is a graph showing the relationship among parameters such as the above-described stop time Te, gas supply valve 10 opening time tf, and drive current If. In terms of equations, equations (5) to (7) correspond.

Ix ″ = Ie−γ · tx ″ (5)
Inclination γ = (Ie−If) / tf (6)
Here, Ie = β · Te + Id (7)
However, Te is an arbitrary stop time of the laser oscillation device. Note that the open time tf of the gas supply valve 10 may be arbitrarily determined. However, if the opening time tf of the gas supply valve 10 is too long, all of the laser medium gas staying in the pipe between the gas cylinder 30 and the gas supply valve 10 of the laser oscillation device will be collected before the blower 4 starts rotating. It is discharged from the laser oscillation device 20 to the outside. In this case, since the calculation by the open time calculator 15 is impossible, tf is preferably several seconds.

In step S08, the blower drive current Ie in the case where the gas supply valve 10 is not opened while the laser oscillation device is stopped from the Te time while the gas pressure is reduced from the gas pressure A to B is calculated in the open time calculator 15. , Calculated from equation (7). The calculated blower driving current Ie is stored in a storage device mounted on the open time calculator 15.

Note that the formula (7) corresponds to the formula (3) in which Tx 'is replaced with Te and Ix' is replaced with Ie.

In step S09, the blower drive current Ie and the gas supply valve 10 when the gas supply valve 10 is not opened while the laser oscillation device is stopped for Te time and the pressure is reduced from the gas pressure A to B are set. A slope γ representing a correlation with the blower drive current If when tf time is open is calculated by the open time calculator 15 using the equation (6). The calculated slope γ is stored in a storage device mounted on the open time calculator 15 (corresponding to the slope of the graph of FIG. 5).

In step S10, the proportionality constant δ for calculating the optimum opening time t of the gas supply valve 10 is calculated from the stop time T of the laser oscillation device from the equation (11) obtained by the following calculation. The calculated proportionality constant δ is stored in a storage device mounted on the open time calculator 15 (the slope of the graph of FIG. 6 corresponds to δ).

From the equation (5) tx ″ = (Ie−Ix ″) / γ (8)
Here, if tx ″ = td, Ix ″ = Id, and further substituting equation (7) into equation (8),
td = (β · Te + Id−Id) / γ = (β / γ) · Te (9)
Generalizing equation (9)
t = δ · T (10)
δ = β / γ (11)
Thereby, the initial setting is completed (step S11).

The meaning of the calculated values γ and δ obtained in the initial setting flow of FIG. 4 will be described in detail with reference to FIG.

The calculated value γ indicates the degree of influence of the opening time of the gas supply valve 10 on the driving current of the blower 4 with respect to the stop time T of the laser oscillation device shown in the graph of FIG. It is possible to obtain the blower drive current Id when the mixing ratio of the laser medium gas supplied to the laser oscillation device 20 is normal based on the calculated value γ. The opening time of the gas supply valve 10 that can obtain the obtained blower driving current Id is the optimum opening time t of the gas supply valve 10.

However, as shown in the graph of FIG. 6, the open time t of the gas supply valve 10 with respect to an arbitrary stop time T of the laser oscillation device is not constant but is a function of the stop time. Ask.

Thereby, a general formula for calculating the optimum opening time t of the gas supply valve 10 with respect to the stop time T of the laser oscillation device is obtained.

The startup of the laser oscillation device after the initial setting is completed is the normal operation in the flowchart of FIG.

In step S12, the stop time T counted by the stop time counter 16 is read. In step S <b> 13, the opening time calculator 15 calculates the opening time t of the gas supply valve 10 at the time of start-up by the equation (10). In step S14, the gas supply valve 10 is opened for time t while the gas pressure is reduced from A to B.

Thereafter, the operation is performed according to the normal sequence of the laser oscillation device (step S15).

If the distance from the gas cylinder 30 to the gas supply valve 10 and the leakage amount specific to the piping member therebetween are known in advance, β, γ, and δ are calculated in advance and tabulated. This eliminates the need for the initial setting processing flow shown in FIG. 3 and greatly reduces the time required for installation of the laser oscillation device.

The laser oscillation apparatus of the present invention has a small pinhole in the pipe between the gas cylinder and the gas supply valve of the laser oscillation apparatus, the laser medium gas leaks, and the mixing ratio of the laser medium gas staying in the pipe changes. However, a stable laser output can be obtained. Furthermore, it is possible to provide a laser oscillation device that reduces the number of valves used, reduces costs, and suppresses consumption of the laser medium gas. This is industrially useful as a laser oscillation device using a laser medium gas.

DESCRIPTION OF SYMBOLS 1 Optical resonator 2 Partial reflection mirror 3 Total reflection mirror 4 Blower 5 Heat exchanger 6 Gas circulation path 7 Laser beam 8 Inverter 9 Current detector 10 Gas supply valve 11 Gas discharge valve 12 Vacuum pump 13 Gas pressure detector 14 Gas pressure controller 15 Open time calculator 16 Stop time counter 20 Laser oscillator 30 Gas cylinder

Claims

A laser oscillation device that continuously or intermittently supplies a laser medium gas from the outside,
An optical resonator;
A gas circuit connected to the optical resonator;
A laser medium gas supplier for supplying a laser medium gas to the gas circulation path or the optical resonator via a gas supply valve;
A gas discharge pump for discharging laser medium gas from the gas circulation path or the optical resonator through a gas discharge valve;
A gas pressure detector for detecting a gas pressure of a laser medium gas in the gas circulation path or the optical resonator;
A gas pressure controller for controlling the gas supply valve and the gas discharge valve based on the gas pressure detected by the gas pressure detector;
A blower provided in the gas circulation path;
A current detector for detecting a blower drive current of the blower;
A stop time counter for counting the stop time when the laser oscillation device is stopped;
A storage device for storing correlation information between the stop time and the blower driving current;
An open time calculator for calculating the open time of the gas supply valve at the time of starting the laser oscillation device according to the information of the storage device,
When starting the laser oscillation device from a stopped state, the gas circulation path and the staying gas inside the optical resonator are discharged from the gas discharge valve opened by the gas pressure controller,
During the time calculated by the open time calculator from the previous stop time of the laser oscillation device, the gas pressure control is performed on the laser medium gas in the pipe between the laser medium gas supply unit and the gas supply valve. A laser oscillation device that discharges together with the staying gas through the gas supply valve opened by a vessel.
At least the first device stop time and the second device stop time are set by an initial setting operation of a sequence different from the normal operation,
In each of the first device stop time and the second stop time,
Driving current of the blower when the laser oscillation device is operated without opening the gas supply valve, and the blower when the laser oscillation device is operated after opening the gas supply valve for a predetermined time The laser oscillation apparatus according to claim 1, wherein the correlation information is calculated from a driving current of the laser.
The laser oscillation device according to claim 1 or 2, wherein the gas supply valve is connected to the optical resonator.
4. The laser oscillation device according to claim 1, wherein the gas discharge valve is connected to the gas circulation path.
The laser oscillation device according to any one of claims 1 to 4, wherein the gas pressure detector is connected between the gas circulation path and the gas discharge valve.